The invention relates to a gas chromatography apparatus.
Gas chromatography apparatuses (GCs) are well-known in the state of the art. These well-known gas chromatography apparatuses comprise a coiled separation column for separating sample components. The separation column is installed in a heatable oven and has a downstream connection with a detector, which detects the different sample components. Further, the separation column comprises an upstream connection with an adsorbent, which is installed in a cold trap. During operation of this type of gas chromatography apparatuses there are two different phases of operation, which will be described in the following.
In the first phase of operation the adsorbent is loaded with the sample components, e.g., atmospheric air containing pollutants. The atmospheric air containing the pollutants is pumped or drawn through the adsorbent, which is cooled during the loading phase. Therefore, the pollution substances contained in the atmospheric air are concentrated in the adsorbent.
After this loading phase, the cooling of the adsorbent is stopped and both the adsorbent and the separation column are heated. Then, the pollution substances concentrated in the adsorbent are purged out of the adsorbent and swept by a gas through the separation column so that the detector detects the different separated pollution substances.
In common gas chromatography apparatus according to the state of the art, the cooling of the cold trap containing the adsorbent is effected by injecting a refrigerant (e.g., liquid nitrogen) into the cold trap, where the liquid nitrogen vaporizes thereby cooling the adsorbent. However, this type of cooling results in a high consumption of the refrigerant.
Therefore, it is an object of the invention to reduce the consumption of the refrigerant in such a gas chromatography apparatus.